Panel lighting systems for residential and commercial applications have increasingly utilized LEDs as a light source due to their high lumen output, decreased energy consumption, and extended life cycle compared to traditional light sources such as fluorescent or incandescent light bulbs. Conventional edge-lit LED panel lighting systems generally include a frame in which white LEDs emit light into the edge of a light guide having features to distribute and emit light for illuminating a room, corridor, or other area. The need for maximum utilization of energy drives the design of components and features that reduce optical losses.
Currently white LEDs are obtained through the down-conversion of a fraction of the blue light emitted from a blue LED chip to produce yellow light, which upon mixing with the remaining (unconverted) blue light yields a spectrum that appears white to the human eye. Conventional white LEDs typically use a coating containing one or more rare-earth-containing phosphors to realize such a color conversion.
However, the conventional implementation suffers from a variety of problems, including far-field color non-uniformity originating from poor control of phosphor dispersion, significantly reduced external quantum efficiency due to phosphor quenching and unfavorable scattering losses, poor color rendition capability of saturated red hues (termed R9), and high material cost at the required phosphor loading level, as well as high binning costs when the lighting application has a tight tolerance for color quality variations.